Saying goodbye definitively to covid is almost a utopia: since the first months of the pandemic, experts had understood that the most probable future scenario would be that of an endemic disease, which will continue to circulate in a less severe form among us. But less serious in what sense? Will it be more like a cold or a seasonal flu? No one has the crystal ball to know what will happen (and we have already seen that even the most reasonable predictions are contradicted by viral evolution), but experts agree that the appearance of the Delta and Omicron variants have messed up the cards on the table. , and suggest that the coronavirus is adapting to bypass our immune defenses and be able to infect even those protected by vaccines or previous infections.
Easily attachable. During the first months of the pandemic, SARS-CoV-2 had free field: he faced guests who had never met him, and were therefore totally vulnerable to infection. In November 2020, the first variant appears in the United Kingdom, the Alpha, at the same time as the Beta in South Africa, and shortly after the Gamma in Brazil: these three VoC (variants of concern, variants of concern) are more contagious than the original strain, and Beta and Gamma are also partially able to reduce the amount of neutralizing antibodies produced by our immune system. It is the first sign that something is changing.
Delta variant. The Delta variant, identified in India in the spring of 2021, turns out to be 60% more contagious than Alpha: it multiplies much faster in the respiratory tract of the infected, and seems to be able to at least partially evade the protection given by vaccines and infections. After some variants that had aroused some concern but which had resolved into a soap bubble, many experts believe that any new variants can only mutate from the Delta, now dominant throughout the planet.
The Omicron Change. But at the end of November, an unexpected new turning point: Omicron appears, identified once again in South Africa (but probably originally from another African country where the genomic sequencing system is not effective) and highly contagious. According to Tom Wenseleers, an evolutionary biologist at the Catholic University of Leuven (Belgium), an increased contagiousness of Omicron cannot be the only explanation for the sudden increase in infections: a more realistic explanation, he argues together with other researchers, is that the of Omicron lies in the ability of also infect those who are vaccinated or cured of covid. If so, claims Sarah Cobey (University of Chicago), this theory would make it clear in which evolutionary direction the SARS-CoV-2 is moving: not that of infinitely multiplying one’s contagiousness, but that of evading the immunity acquired by who has already been infected e fish out guests already infected, making their targets potentially unlimited.
An unknown future. This evolutionary path towards immune evasion is common to several respiratory viruses, such as the flu: “The simplest way for a virus to cause epidemics that last over time is to evade immunity: that’s what seasonal coronaviruses do »Explains Adam Kucharski (London School of Hygiene and Tropical Medicine). How the coronavirus evolves will affect its transition to an endemic virus: right now, the most likely future scenario looks like a flu-like virus, with peaks of seasonal infections and the need for periodic updating of vaccines. The frequency of these updates is unpredictable, and will depend on how quickly SARS-CoV-2 mutates to circumvent the immunity of its hosts (us). But the future, Nature recalls, could still be in our hands: vaccinating as many people as possible, as long as the doses we have available are still effective, could be the key to preventing the virus from mutating again and triggering a new wave of infections.